Pneumatic web control device



June 19, 1962 L. CAMPBELL ETAL 3,039,714

PNEUMATIC WEB CONTROL DEVICE 3 Sheets-Sheet 1 Filed Jan. 15. 1958 FIG. I

INVENTORS ALBERT L. PETERSON LEONARD CAMPBELL EMQ M m,@amn

PA A ZRNEYS FLOATING ROLLE DERS TENSION CYLINDER PRESSU BUILD CYLI N m Ts F o E m T June 19, 1962 CAMPBELL ETAL 3,039,714

PNEUMATIC WEB CONTROL DEVICE Filed Jan. 15, 1958 FIG. 3

3 Sheets-Sheet 2 NTROL VALVE I 2 PER AIR MOTOR INVENTORS ALBERT L.PETERSO LEONARD CAMPBELL ATT RNEYS June 19, 1962 CAMPBELL ETAL 3,039,714

PNEUMATIC WEB CONTROL DEVICE Filed Jan. 15. 1958 5 Sheets-Sheet 3INVENTORS ALBERT L.PETERSON LEONARD CAMPBELL ATTOR EY S I United StatesPatent Ofiflce 3,639,714 Patented June 19, 19-62 3,039,714 PNEUMATIC WEBCONTROL DEVICE Leonard Campbell, New Brunswick, and Albert L. Peterson,Westfield, N.J., assignors to Wood Newspaper Machinery Corporation,Plainfield, N.J., a corporation of Virginia Filed Jan. 15, 1958, Ser.No. 709,152 6 Claims. (Cl. 242-7542) This invention relates generally toa pneumatic Web control device and more particularly to an automatic webtensioning device incorporating a floating roller for maintainingsubstantially constant tension in a running web, pneumatic braking meansactuated by movement of the floating roller for braking a rotatingsupply roll, and rate means for adjusting the characteristics ofresponse of the brake means to the movement of the floating roller.

A prime requirement of high speed printing presses such as used inprinting newspapers, is that the running web of paper passing to theprinting press be kept at a substantially constant tension. If, for anyreason, the tension of the web increases considerably, there is dang rthat the Web will break. On the other hand, if the tension of the webdecreases below a predetermined value, there is danger that the web willbunch up before entering the press. This latter condition will usuallyoccur when the web is supplied from a rotating supply roll, which, dueto its heavy mass, will tend to run ahead of the press if the pressspeed drops suddenly and if the floating roller and tensioning deviceare incapable of overcoming the change in tension of the running web.

The weight of a floating roller and the pivoted arm to which it isattached becomes an important factor in maintaining constant web tensionwhen the pivoted arm moves beyond its vertical axis running through itspivot point. Thus, in application Serial No. 624,790 entitled, WebTensioning Device, filed November 28, 1956, by A. L. Peterson, there isdisclosed a spring for overcoming the weight of the floating roller andthe arm to which it is mounted when the arm swings beyond its verticalaxis. This application further discloses an electrical relay systemincorporated in the brake control of the press Which will apply brakingforce to the rotating supply roll be fore the brakes of the press areactuated in order to compensate for the inertia of the rotating supplyroll during an emergency stop of the press.

We propose in our present invention to eliminate the separate springshown in the previously mentioned application which compensates for theweight of the roller and arm by utilizing a balance spring included in apneumatic control valve. We further propose to provide for an easilyadjustable rate means for varying the speed of response, amount andduration of reaction means used to return the floating roller to anoriginal position so that substantially constant tension may bemaintained on a web even during emergency stop of a web handling machinewithout the necessity of incorporating a phased electrical relay systembetween the brakes of the machine and the supply roll.

Broadly, We propose to use a variable pneumatic pressure control valvewhich has therein a pressurized reaction chamber having a flexiblediaphragm at one end for overcoming the force necessary to depress aspring biased inlet valve contained in the control valve which allowspressurized air to be admitted to a tension cylinder and which returnsthe control valve to a balanced state. The tension cylinder in turnexerts pressure on a tension belt which passes over the rotating supplyroll. A floating roller mounted on a pivoted arm is positioned betweenthe machine and the rotating supply roll so that the running web willpass over its surface. The pivoted arm is urged in one direction bymeans of a reference force air motor and is pulled in the oppositedirection by the tension of the web on the floating roller. Movement ofthe arm will actuate the control valve to allow air to be eitherexhausted from the tension cylin der or to be admitted thereto from asource of pressure.

Conduit means connect the reaction chamber of the control valve eitherwith the tension cylinder or with a control pressure outlet port of thecontrol valve so that pneumatic pressure in the reaction chamber willcause the flexible diaphragm to move and to compensate and oppose theforce necessary to actuate the control valve. Rate of flow means areprovided in the conduit for adjusting rate of flow of pressure air intothe reaction chamber in order that the period and amount of responsebetween application of braking force on the supply roll and return ofthe control valve to its balance position may be varied. The overalleffect of such a system is to apply an initially greater pressure in thetension cylinder than is normally needed to maintain constant tension.

Referring to the drawings which illustrate a preferred embodiment of ourinvention,

FIG. 1 is a schematic view illustrating the position of the differentparts of the web tensioning device with respect to supply rolls;

FIG. 2. is a graph illustrating pressure built up in the tensioncylinder with regard to receipt of a stop signal by the press;

FIG. 3 is an enlarged side view of the floating roller and associatedparts shown in FIG. 1;

FIG. 4 is an enlarged cross-sectional view of the control valve shown inFIG. 3; and

FIG. 5 is a partial View of FIG. 4 ilustrating a slightly differentembodiment of means for varying the rate of response of the brake meansincorporated in the tensioning device.

Referring initially to FIG. 1, supply rolls 1, 2 and 3 supply a web 4 toa web handling machine, normally a printing press, not shown. Asillustrated in FIG. 1, web 4 is initially run off supply roll 1, whilesupply rolls 2 and 3 are reserve rolls which may swing in to paste ontoweb 4 when roll 1 is exhausted. A tension belt 5 passes over a portionof supply roll 1 so that when tension of the belt is increased bymovement of the piston 6 in tension cylinder 7, a braking force will beimparted to the rotating roll. Tension cylinder 7 is in turn connectedby conduit 8 to a control valve denoted generally by the numeral 9 inFIG. 3.

A floating roller 10 mounted on a pivoted arm 11 is placed between therotating supply roll and the web handling machine and serves to providea measure of constant tension in the running web. The arm 11, as shownin FIG. 3, is urged in a counterclockwise direction by means of areference force air motor 12 which is connected by means of a conduit 13to manual pressure con trol valve 14. Arm 11 is urged in a clockwisedirection by the tension existing in the running web 4. A conventionaldamper 15 serves to slow the movement of the arm 11 about the pivotpoint 16 and to reduce hunting of the arm. The control valve 9, airmotor 12, damper 15, and the linkage connecting these parts with the arm11 are all incased within a housing 80.

Control valve 9 is actuated by movement of the floating roller 10 andarm 11 through link 20 and arm 21. Arm 21 is pivoted about the point 22so that when the floating roller and arm 11 move in a counterclockwisedirection, arm 21 will rotate about point 22 to depress a piston 30which is slidable in housing 31 of the control valve 9. Roller 32 ismounted on the end of arm 21 in order to reduce friction of contactbetween the arm and the piston. Adjustable stops 33 and 33' limitmovement of the arm 21 while adjustable stops 34 and 34' limit movementof arm 11 by hearing on portion 35 and 3-5 thereof.

Control valve 9 has a flexible diaphragm 40 having therein an aperturethrough which a tube 41 is fixedly attached. Piston 30 is biasedoutwardly of the housing by means of control spring 42 and is movablewith respect to tube 41. Spring 42 is of such strength as to balance;the effect of gravity on floating roller 1%) and arm 11 when the armswings beyond its vertical axis. Piston '30, housing 31, flexiblediaphragm 40 and tube 41 all cooperate to form an exhaust chamber 43which is connected to a conduit not shown, which in turn leads toatmospheric pressure.

The side of the diaphragm opposite spring 42 forms with housing 31 andtube 41 a reaction chamber 44 which has therein a spring 45 biasing saiddiaphragm to the left as shown in FIG. 4 against the force of spring 42.Reaction chamber 44 is connected by means of conduit 4-3 to tensioncylinder 7 as shown in FIG. 1 so that pressure buildup in the chamber isdependent on pressure in the tension cylinder. A rate valve 47 inconduit 46 varies the rate of pressure build-up in the reaction chamber.

Tube 41 terminates at one end in an exhaust valve seat 50 which isadapted to be sealed by valve face 51 of slidable poppet 52. Poppet 52has on the end opposite that of face 51 a valve face 53 which cooperateswith seat 54 to form an inlet valve. Poppet 52 is biased to the left asshown in FIG. 4 by means of spring 55. The space between valve faces '51and 53 comprises a pressure chamber 56 which is connected by means ofconduit 8 with tension cylinder 7. Inlet valve 53 opens into conduit 57which is connected to a source of pressure, not shown. The pressurechamber 56 is sealed from the exhaust chamher by means of ring '58carried in the lower half of housing 31 and through which tube 41 mayslide when moved by diaphragm 49.

A slightly modified form of the invention is shown in FIG. Where aconduit 60 connecting pressure chamber 56 with reaction chamber 44.Conduit 60 has therein an adjustable rate valve 61 to vary the rate ofpressure buildup in the reaction chamber until it equals the pressure inthe pressure chamber. It is to be understood that the size of thepressure chamber 62 varies with the length of conduit 60 and with thedesired rate of pressure build-up in the reaction chamber. When thisform of the invention is used, conduit 69 is, in effect, substituted forconduit 46.

The operation of the device to maintain substantially constant tensionin the web throughout all phases of press operation is readily apparentby referring to FIGS. 1, 3 and 4. A desired pressure to give a desiredtension in the web is initially set in the system by means of manualpressure control 14. This in turn will impart pressure in referenceloading air motor 12 which will move arm 11 in a counterclockwisedirection to put tension into web 4.

Arm 11 will move to the left under the influence of pressure in the airmotor. This in turn will move link 20 and arm 21 so at to depress piston30 in the control valve. Depression of piston 30 will in turn exert aforce on control spring 42 causing flexible diaphragm 40 and 41 to movein a right hand direction from a neutral position as shown in FIG. 4.This movement of tube 41 will bring exhaust seat 59 into contact withexhaust face 51 of the poppet 52 to close the exhaust port. Furthermovement of the tube 41 will depress poppet 52 against spring 55 to openthe inlet port and so allow admission of pneumatic pressure from conduit57 into the chamber 56. Increase of pressure in pressure chamber 56 willin turn be transmitted to the tension cylinder 7 through conduit 8 tocause piston 6 to move to the left to increase the tension in tensionbelt 5 and so exert a braking force on the rotating supply roll 1. As aresult the rotating supply roll will slow down and so tend to increasethe tension in the moving web which will cause arm 11 and floatingroller to move back in a clockwise direction.

' The weight of floating roller 1t) and arm 11 have an increasing momentabout the pivot point 16 as they move to the left. Under static or slowchanging conditions, this moment is balanced by the compression ofspring 42 when flexible diaphragm 40 is in a neutral or nearly neutralposition, as shown in FIG. 4, and when control valve 9 is in a balancedposition neither delivering to nor exhausting appreciable amounts of airfrom cylinder 7.

However, when the change in tension is appreciable and such that theflexible diaphragm is moved rapidly to the right as shown in FIG. 4, thespring 42 must be compressed to a shorter length in order to generate aforce suflicient to balance the moment due to the weight of the arm 11and roller 10 in their new position. This is accomplished by havingpressure build-up in the reaction chamber 44 to eventually equal that inthe tension cylinder 6 or, as shown in alternate embodiment, thepressurized chamber 62, which will cause diaphragm 46 to return to itsoriginal position and so compress spring 42.

Any delay in pressure build-up in conduits 46 or 60 Will in turn cause adelay in pressure build-up in the reaction chamber and a consequentdelay in the spring 42 being able to produce a balancing force. Thisdelay in producing a balancing force will result in the rollercontinuing its movement to the left under the force of the air motor andincreasing moment. The result is that the diaphragm will move evenfurther to the right and so allow even more pressure build-up in thetension cylinder.

This motion of the floating roller might be considered as a selfenergizing action which tends to increase the amount of air flow to thetension cylinder and thus speed up the corrective action. Further, thefalling over of the floating roller tends to take up web loop rapidly astension of the web decreases.

It can be cited that the reverse of the above operation can occur ifthere is an increase in tension. The self energizing action can occurbut in the opposite sense. In other words, the floating roller becomeslighter and the corrective action is sped up from the tension cylinder.

When tension in the web has been increased by application of brakingforce on the rotating supply roll and after the pressure in the reactionchamber is equal to that in the tension cylinder or chamber 62, the arm11 and roller will move to the right. Spring 45 and pressure in reactionchamber 44 will then move diaphragm 40 to the left back to the neutralposition. Any further movement of the diaphragm to the left, will openthe exhaust port so allowing pressure to exahust from tension cylinder 7to decrease tension in the web.

If the web handling machine speeds up momentarily, the tension of theweb will increase so causing arm 11 to rotate in a clockwise direction.This will in turn allow piston 30 to move outwardly of the control valveand to let the flexible diaphragm 40 and tube 41 move to the left underthe influence of pressure in the reaction chamber 44 and spring 45 withthe result that the exhaust valve will open while the inlet valveremains closed. Pressure in the tension cylinder and thus braking of thesupply rolls will, therefore, decrease to compensate for the increase oftension in the web due to the increase in machine speed.

If there is an emergency stop of the machine so that the tension in web4 drops sharply, it is obvious that floating roller 10 will move quicklyto the left in order to compensate for the sharp decrease in tension.This in turn will move piston 30 violently against spring 42 andflexible diaphragm 40 and so cause the tube 41 to open the inlet port atvalve 53 to allow a large amount of pressure build-up in the tensioncylinders. There will be a momentary period of time before pressure inthe reaction chamber 44 will build up to equal the pressure exerted inthe tension cylinder, as shown in FIG. 4, or the pressure chamber, asshown in FIG. 3, due to the pressure drop across either rate controlvalves 47 or 61. During the period while pressure in the reactionchamber is building up, maximum pressure will be exerted on the tensioncylinder while at the same time the floating roller will be seeking itsmaximum pressure or tension position. The net result of incorporating arate control means in the control valve is that pressure build-up in thetension cylinders may be accelerated with relation to receipt of a stopsignal by the web handling machine. This feature is shown in FIG. 2which is a graph illustrating rate of pressure build-up in tensioncylinders with respect to receipt of a stop signal by a press. It isseen from an inspection of FIG. 2, that pressure builds up in thetension cylinder faster when rate control means are provided.

We have found that by incorporating a tension control device such asdisclosed, that substantially constant tension may be maintained on amoving web under all conditions of web handling machine operatingspeeds. The rate control means disclosed provides a practical andeflicient means of varying the rate of braking force to be applied to arotating supply roll with the movement of a floating roller while at thesame time compensating for the inertia of the heavy rotating supplyroll.

Having described our invention, reference should now be had to theclaims which follow for determining the scope thereof.

We claim:

1. A web tensioning device for controlling tension of a web running froma rotating supply roll to a web han dling machine under all runningspeeds, comprising a vertically extending floating roller pivoted forrotation about its lower end contacting said web to measure and maintainsubstantially constant tension in said movable Web, a variable pressurecontrol valve connected to a source of pressure and actuated by movementof said floating roller, a pressure chamber in said control valve, areaction chamber in said control valve communicating with said pressurechamber, a flexible diaphragm comprising one side wall of said reactionchamber, a control spring bearing on said diaphragm and positionedbetween said diaphragm and said floating roller to compensate for changeof effective Weight of said floating roller due to movement beyond thevertical axis, pressure operated braking means operable by actuation ofsaid variable pressure control valve for exerting braking force on saidrotating supply roll, and rate control means for varying the rate ofpressure build up in said reaction chamber when said variable pressurecontrol valve is actuated by movement of said floating roller.

2. A web tensioning device controlling tension of a web running from arotating supply roll to a press, comprising a floating roll contactingsaid web, a vertically extending arm pivoted for rotation about afulcrum at its lower end and having said roller mounted on one endthereof, motor means urging said arm and roller in a direction aboutsaid fulcrum to increase tension in said web, a variable pressurecontrol valve connected to a source of pressure and actuated by movementof said floating roller and arm about said fulcrum, a pressure chamberin said control valve, a reaction chamber in said control valvecommuting with said pressure chamber, a flexible diaphragm comprisingone side of said reaction chamber, a control spring bearing on saiddiaphragm and positioned between said diaphragm and said arm tocompensate for change of moments due to change of position of said armand roller about said fulcrum, pressure operated braking means operableby actuation of said variable control valve for exerting braking forceon said rotating supply roll, and rate control means for varying therate of pressure build up in said reaction chamber when said variablepressure control valve is actuated by movement of said arm to increasepressure in said pressure chamber; pressure build up in said reactionchamber causing said diaphgram to move against said control spring toreturn said variable pressure control valve to a neutral position.

3. A web tensioning device according to claim 2 wherein said reactionchamber connects by a conduit to said pressure chamber and said ratecontrol means are interposed in said conduit.

4. A web tensioning device according to claim 2 wherein said brakingmeans comprises a pneumatic tension cylinder in communication with saidpressure chamber whereby admission of pressure in said pressure chamberincreases pneumatic pressure in said cylinder to increase braking forceon said rotating supply roll.

5. A web tensioning device according to claim 4 wherein said reactionchamber connects by a conduit to said tension cylinder and said ratecontrol means are interposed in said conduit.

6. In a web tensioning device for controlling tension of a web runningfrom a rotating supply roll to a press by means of a floating rollermounted on a vertically extending arm movable about a fulcrum located onthe lower end of said arm wherein movement of said arm in response tochange of tension in said web varies braking force applied to saidrotating supply roll; the improvement comprising a variable pressurecontrol valve having therein a pressure chamber, an exhaust chamber anda reaction chamber, a piston movable in said exhaust chamber and inresponse to movement of said arm, a first spring urging said pistonoutwardly of said exhaust chamber to balance moments due to the weightsof said arm and roller when out of vertical alignment, a flexiblediaphragm separating said exhaust chamber and said reaction chamber andbearing on said first spring, a second spring in said reaction chamberurging said diaphragm in a direction opposite to said first spring, amovable poppet having thereon an exhaust face and an inlet face, anexhaust seat fixedly positioned with respect to said flexible diaphragmadapted to engage said exhaust face, an inlet seat fixedly positionedwith respect to said housing and adapted to engage with said inlet face,a third spring biasing said poppet to seat said inlet face on said inletseat, conduit means connecting said pressure chamber with said reactionchamber, and rate control means interposed in said conduit means forvarying the rate of pressure build up from said pressure chamber to saidreaction chamber.

References Cited in the file of this patent UNITED STATES PATENTSGermany July 21, 1952

